Many electronic circuits are designed for use with a constant current input or bias signal, which may be provided by a constant current source. For example, constant current sources are regularly employed in biasing input buffer circuits, delay circuits, and/or oscillator circuits. Traditional constant current sources employ a bandgap reference circuit using multiple amplifiers. The multiple amplifiers, however, consume substantial power and take up significant space in the circuit. Additionally, multiple amplifier bandgap reference circuits may still suffer from some current variation across operating temperatures.